CONWAY (AP) — A $135 million project to widen Interstate 40 to six lanes between Conway and the Interstate 430 interchange near Little Rock will take place with minimal lane closures, highway officials said Tuesday.

Most of the work on the 23-mile stretch will take place in the median, where the new lanes are being added.

Two sets of bridges along Lake Conway will be replaced and widened, as will the overpass at U.S. Highway 65 in Conway. That work will necessitate occasional lane closures but most of the work will be done with lane shifts that will keep all four traffic lanes clear.

“We’re already at congestion with the lanes we’ve got,” said Emanuel Banks, assistant chief engineer for the Arkansas Highway and Transportation Department.

More than 70,000 vehicles travel I-40 at the I-430 interchange daily.

The first of four phases of work is under way, something that is plain to motorists driving by the concrete segments flagged with orange reflectors that line the outside lanes of traffic in both directions.

“We’ll be working behind the barrier,” said Mark Windle, a division manager with Manhattan Road and Bridge Co. of Little Rock, the company that is performing the bridge portions of the work.

The first phase of the work — eight miles that run from U.S. 65 eastward — is to be completed in 2014. The other phases will be bid out next year. Highway department spokesman Glenn Bolick said the timing of that work depends on funding. Completion of the project is among the promised improvements if voters approve a half-cent sales tax increase that will appear on the November ballot, he said.

That ballot measure is a companion piece to a $575 million bond proposal that voters approved last November, a vote that dedicated 4 cents of the state’s 22.5-cent diesel tax to paying off the bonded indebtedness.

The coming sales tax proposal may not have as easy a time at the ballot as last year’s proposal, which passed in each of the state’s 75 counties.

Once complete, drivers on I-40 will have six lanes to travel from the middle of Conway to the east side of North Little Rock.

The highway is an important cross-country truck route that stretches from California to North Carolina.

But Conway Mayor Tab Townsell noted that about half the motorists who use the highway in Conway are just taking short trips through the city.

“This is our community that uses this street,” Townsell said. “Most of the traffic here isn’t leaving the state.”

Townsell asked drivers to be attentive and patient.

The concrete barriers are right at the edge of the inside lanes, so there are no emergency lanes at the median. That gives vehicles less room to maneuver in the event of a sudden stop or while trying to get out of the way of a distracted driver.

“Please drive slow, drive in place and live,” Townsell said.

Highway officials noted that this week is National Work Zone Awareness Week. Highway fatalities have been on the decline in Arkansas since 2006, when 665 people died on state roads. In 2010, there were 563 fatal crashes. That’s 19.27 fatalities for every 100,000 people in the state, nearly double the national average of 10.63 deaths per 100,000 people, according to the National Highway Traffic Safety Administration.